A laser device that amplifies pulse light that has been chopped by an electro-optic modulator and then wavelength converts and outputs it is known as being an appropriate light source for a microscope, a shape measurement device, an exposure device or the like (refer to Patent Document #1). An electro-optic modulator (EOM: Electro-Optic Modulator) is an optical modulator that utilizes the electro-optic effect of a ferroelectric material such as LiNbO3 (lithium niobate) to modulate and output the phase and amplitude and so on of input light with an electrical signal. An EOM of the Mach-Zender type is widely used as an intensity modulator that modulates the amplitude of the input light, in other words its intensity.
An EOM of the Mach-Zender type is constructed to change the refractive indexes of two optical paths that constitute a Mach-Zender interferometer, so that a phase difference between the light beams propagated along these optical paths is generated, and thus the intensity of the output light is changed. In other words, it is possible to perform high speed ON/OFF control of the light incident upon the electro-optic modulator by controlling the voltages applied to these two optical paths: for example, it is possible to make a structure that outputs pulse light by chopping around 1 nsec from seed light whose ON period is around 10 nsec (refer to Patent Document #2).